The present invention relates generally to optical network systems, and more particularly to a system and method for providing data channel reservation in an optical burst-switched network.
Data traffic over networks, particularly the internet, has increased dramatically over the past several years, and this trend will continue with the introduction of new services which require more bandwidth. The enlarged volume of internet traffic requires a network with high capacity routers capable of routing data packets with variable lengths. One option is the use of optical networks. However, current optical networks use only a small fraction of the bandwidth available on a single optical fiber.
The emergence of dense-wavelength division multiplexing (DWDM) technology has helped to overcome the bandwidth problem encountered by current optical networks. A single DWDM optical fiber has the capability of carrying as much as ten (10) terabits of data per second. Different approaches advocating the use of optical technology in place of electronics in switching systems has been proposed, however the limitations of optical component technology has largely limited optical switching to facility management applications. One approach called optical burst-switched networking attempts to make the best use of optical and electronic switching technologies. The electronics provides dynamic control of system resources, assigning individual user data bursts to channels of a DWDM fiber. Optical technology is used to switch the user data channels entirely in the optical domain.
One problem with switching user data channels entirely in the optical domain is that it is difficult to setup a data channel path across an optical burst-switched network without wasting network resources such as transmission and switching capacity. Each data channel within an optical path can range from ten (10) Gbps to forty (40) Gbps and the roundtrip delay of an optical path is very long when using conventional signaling approaches. Thus, setting up an optical path with bandwidth of one or more data channels in an optical burst-switched network takes a long time and wastes a huge amount of bandwidth. If the connection time is not sufficiently long, the bandwidth wasted may not be well justified.
Another problem with optical burst-switched networks relates to data channel scheduling. Schedulers within switch control units of core routers in the optical burst-switched network are responsible for scheduling burst payloads and their corresponding burst header packets on data channel groups (DCG) and control channel groups (CCG), respectively. A burst header packet has to be processed in the switch control unit as quickly as possible, thus the scheduling algorithm must be simple and fast.
One prior art scheduling algorithm is the Latest Available Unscheduled Channel (LAUC) algorithm , also known as the Horizon algorithm. In the LAUC algorithm, only one value, the future available/unscheduled time, is remembered for each data channel. However, the LAUC algorithm results in high burst loss ratio and thus low channel utilization due to the gaps/voids between bursts. Other more sophisticated scheduling algorithms usually lead to less burst loss ratio, but their implementation are very difficult since the scheduler has to work at a very high speed (e.g., about 100 nanoseconds per burst). Thus, a simple and fast scheduling algorithm is needed to reduce the burden of schedulers in optical burst-switched networks and to improve the performance of data channel scheduling.
The present invention provides an optical burst-switched network that substantially eliminates or reduces disadvantages and problems associated with previously developed optical burst-switched networks used for switching data channels.
More specifically, the present invention provides a system and method for reserving data channels in an optical burst-switched network. A data channel along an optical path in an optical burst-switched network is reserved by first transmitting a data channel reservation request from an electronic ingress edge router to a reservation termination node. Next, the data channel reservation request is processed at the reservation termination node. A data channel reservation acknowledgement is then transmitted from the reservation termination node to the electronic ingress edge router. Finally, the data channel path is reserved once an initial burst(s) which contains a reserve data channel bit reaches the reservation termination node.
The present invention provides an important technical advantage by providing a mechanism to use xe2x80x9ccross connectxe2x80x9d in the optical burst-switched network whenever possible without losing the efficiency and flexibility of burst switching.
The present invention provides another technical advantage by avoiding unnecessary hop-by-hop burst scheduling.
The present invention provides yet another technical advantage by reducing the load on schedulers of switch control units in optical core routers.
The present invention provides yet another technical advantage by reducing the gaps/voids between bursts transmitted on the reserved data channels, which in turn increases the data channel utilization.